1,263 research outputs found
Strange Particles from NEXUS 3
After discussing conceptual problems with the conventional string model, we
present a new approach, based on a theoretically consistent multiple scattering
formalism. First results for strange particle production in proton-proton
scattering at 158 GeV and at 200 GeV (cms) are discussed.Comment: invited talk, given at the Strange Quark Matter Conference, Atlantic
Beach, North Carolina, March 12-17, 200
A Suborbital Payload for Soft X-ray Spectroscopy of Extended Sources
We present a suborbital rocket payload capable of performing soft X-ray
spectroscopy on extended sources. The payload can reach resolutions of
~100(lambda/dlambda) over sources as large as 3.25 degrees in diameter in the
17-107 angstrom bandpass. This permits analysis of the overall energy balance
of nearby supernova remnants and the detailed nature of the diffuse soft X-ray
background. The main components of the instrument are: wire grid collimators,
off-plane grating arrays and gaseous electron multiplier detectors. This
payload is adaptable to longer duration orbital rockets given its comparatively
simple pointing and telemetry requirements and an abundance of potential
science targets.Comment: Accepted to Experimental Astronomy, 12 pages plus 1 table and 17
figure
Characterizing Ultraviolet and Infrared Observational Properties for Galaxies. I. Influences of Dust Attenuation and Stellar Population Age
The correlation between infrared-to-ultraviolet luminosity ratio and
ultraviolet color, i.e. the IRX-UV relation, was regarded as a prevalent recipe
for correcting extragalactic dust attenuation. Considerable dispersion in this
relation discovered for normal galaxies, however, complicates its usability. In
order to investigate the cause of the dispersion, in this paper, we select five
nearby spiral galaxies, and perform spatially resolved studies on each of the
galaxies, with a combination of ultraviolet and infrared imaging data. We
measure all positions within each galaxy and divide the extracted regions into
young and evolved stellar populations. By means of this approach, we attempt to
discover separate effects of dust attenuation and stellar population age on the
IRX-UV relation for individual galaxies. In this work, in addition to dust
attenuation, stellar population age is interpreted to be another parameter in
the IRX-UV function, and the diversity of star formation histories is suggested
to disperse the age effects. At the same time, strong evidence shows the
necessity of more parameters in the interpretation of observational data, such
as variations in attenuation/extinction law. Fractional contributions of
different components to the integrated luminosities of the galaxies suggest
that the integrated measurements of galaxies which comprise different
populations would weaken the effect of the age parameter on IRX-UV diagrams.
The dependance of the IRX-UV relation on luminosity and radial distance in
galaxies presents weak trends, which offers an implication of selective
effects. The two-dimensional maps of the UV color and the
infrared-to-ultraviolet ratio are displayed and show a disparity in the spatial
distributions between the two parameters in galaxies, which offers a spatial
interpretation of the scatter in the IRX-UV relation.Comment: 23 pages, 27 figures, 4 tables; accepted for publication in The
Astrophysical Journal; re-typesetted in the emulateapj style; minor
corrections in the figure symbols and in the tex
Multilevel Deconstruction of the In Vivo Behavior of Looped DNA-Protein Complexes
Protein-DNA complexes with loops play a fundamental role in a wide variety of
cellular processes, ranging from the regulation of DNA transcription to
telomere maintenance. As ubiquitous as they are, their precise in vivo
properties and their integration into the cellular function still remain
largely unexplored. Here, we present a multilevel approach that efficiently
connects in both directions molecular properties with cell physiology and use
it to characterize the molecular properties of the looped DNA-lac repressor
complex while functioning in vivo. The properties we uncover include the
presence of two representative conformations of the complex, the stabilization
of one conformation by DNA architectural proteins, and precise values of the
underlying twisting elastic constants and bending free energies. Incorporation
of all this molecular information into gene-regulation models reveals an
unprecedented versatility of looped DNA-protein complexes at shaping the
properties of gene expression.Comment: Open Access article available at
http://www.plosone.org/article/fetchArticle.action?articleURI=info%3Adoi%2F10.1371%2Fjournal.pone.000035
Quantum Many-Body Phenomena in Coupled Cavity Arrays
The increasing level of experimental control over atomic and optical systems
gained in the past years have paved the way for the exploration of new physical
regimes in quantum optics and atomic physics, characterised by the appearance
of quantum many-body phenomena, originally encountered only in condensed-matter
physics, and the possibility of experimentally accessing them in a more
controlled manner. In this review article we survey recent theoretical studies
concerning the use of cavity quantum electrodynamics to create quantum
many-body systems. Based on recent experimental progress in the fabrication of
arrays of interacting micro-cavities and on their coupling to atomic-like
structures in several different physical architectures, we review proposals on
the realisation of paradigmatic many-body models in such systems, such as the
Bose-Hubbard and the anisotropic Heisenberg models. Such arrays of coupled
cavities offer interesting properties as simulators of quantum many-body
physics, including the full addressability of individual sites and the
accessibility of inhomogeneous models.Comment: overview article, 27 pages, 31 figure
Qubit portrait of the photon-number tomogram and separability of two-mode light states
In view of the photon-number tomograms of two-mode light states, using the
qubit-portrait method for studying the probability distributions with infinite
outputs, the separability and entanglement detection of the states are studied.
Examples of entangled Gaussian state and Schr\"{o}dinger cat state are
discussed.Comment: 20 pages, 6 figures, TeX file, to appear in Journal of Russian Laser
Researc
Small but crucial : the novel small heat shock protein Hsp21 mediates stress adaptation and virulence in Candida albicans
Peer reviewedPublisher PD
Biochemical and Molecular Mechanisms of Folate Transport in Rat Pancreas; Interference with Ethanol Ingestion
Folic acid is an essential nutrient that is required for one-carbon biosynthetic processes and for methylation of biomolecules. Deficiency of this micronutrient leads to disturbances in normal physiology of cell. Chronic alcoholism is well known to be associated with folate deficiency which is due, in part to folate malabsorption. The present study deals with the mechanistic insights of reduced folate absorption in pancreas during chronic alcoholism. Male Wistar rats were fed 1 g/kg body weight/day ethanol (20% solution) orally for 3 months and the mechanisms of alcohol associated reduced folate uptake was studied in pancreas. The folate transport system in the pancreatic plasma membrane (PPM) was found to be acidic pH dependent one. The transporters proton coupled folate transporter (PCFT) and reduced folate carrier (RFC) are involved in folate uptake across PPM. The folate transporters were found to be associated with lipid raft microdomain of the PPM. Ethanol ingestion decreased the folate transport by reducing the levels of folate transporter molecules in lipid rafts at the PPM. The decreased transport efficiency of the PPM was reflected as reduced folate levels in pancreas. The chronic ethanol ingestion led to decreased pancreatic folate uptake. The decreased levels of PCFT and RFC expression in rat PPM were due to decreased association of these proteins with lipid rafts (LR) at the PPM
Algorithms in nature: the convergence of systems biology and computational thinking
Biologists rely on computational methods to analyze and integrate large data sets, while several computational methods were inspired by the high-level design principles of biological systems. This Perspectives discusses the recent convergence of these two ways of thinking
- …